Let us begin...
When a robbery turns into a homicide, the intelligence unit will investigate to find out that the suspect is someone close.
When Ruzek and Atwater meet up with Ruzek's CI, Ray, who happens to be a former cop, trying to get information. They get a call of an apartment robbery that also turned homicide when a little boy got shot in the head while just laying on the couch.
The investigation leads to Latin gangs, but it seems that the Intel that Ruzek and Atwater got was false and questioned Ray about it. But the investigation leads to another way that all of this could be connected to a dirty cop, who happens to be in the narcotics unit, who's had records of making connections to gang members. But it turns out that the cop happens to be set up after she realized that she let her Intel use her place a couple of times. That Intel happens to be Ray.
Ruzek and Atwater try to stop him as Ray was packing up at his boat but Ruzek crashes his party, and the two meet face to face as he tries to get Ruzek to shoot him. But that wasn't going to happen as Ray was bluffing to Ruzek about having a gun thanks to Atwater tough tackles.
Meanwhile, it seems that Al's luck isn't going the way that he or Voight was hoping for as Voight got inside information about the witness who saw Al and Erin dumping that body. Al remembers him, who was trying to break into his car that night and wants to see him. But Voight won't let that happen as he doesn't want him to jeopardize this.
Voight meets with the witness, who thinks that he was selling drugs but was lending some money from a friend and not to mention spotted him at an addiction group meeting. Al gets worried and tries to call their bluff by filling out his retirement papers, but later Al battles with demons as he plants drugs in the witness' car and gets busted for it. But word gets to Trudy and Voight that Al's pension has been on hold.
"Payback" was a good episode from start to finish. It may not be one of the best episodes this season, but it sure was entertaining and satisfying to watch. I find the character development between Ray and Ruzek okay as there wasn't much to go on but just that it seems that they were former partners but never really give why Ray was like this to Ruzek. Overall, I give this episode 8/10.
You can catch Chicago PD Wednesdays at 10/9c on NBC.